All hopes for the 6.6 are lost if they first put in the 4.5 ohc enging.GM will want to maximise it's R&D cost and get at least 4 modle years of profits before makeing another engine change .also I dont think they can figure out how to get the Alli in there and with the 6.6 you will need the Alli to take a full power 6.6 D Max .
